On IP-over-WDM integration

Expanding Internet-based services are driving the need for evermore bandwidth in the network backbone. These needs will grow further as new real-time multimedia applications become more feasible and pervasive. Currently, there is no other technology on the horizon that can effectively meet such a demand for bandwidth in the transport infrastructure other than WDM technology. This technology enables incremental and quick provisioning up to and beyond two orders of magnitude of today's fiber bandwidth levels. This precludes the need to deploy additional cabling and having to contend with right-of-way issues, a key advantage. Hence, it is only natural that over time optical/WDM technology will migrate closer to the end users, from core to regional, metropolitan, and ultimately access networks. At present, WDM deployment is mostly point-to-point and uses SONET/SDH as the standard layer for interfacing to the higher layers of the protocol stack. However, large-scale efforts are underway to develop standards and products that will eliminate one or more of these intermediate layers (e.g., SONET/SDH, ATM) and run IP directly over the WDM layer. IP over WDM has been envisioned as the winning combination due to the ability of the IP to be the common revenue-generating convergence sublayer and WDM as a bandwidth-rich transport sublayer. Various important concerns still need to be addressed regarding IP-WDM integration. These include lightpath routing coupled with tighter interworkings with IP routing and resource management protocols, survivability provisioning, framing/monitoring solutions, and others     

Initial implementations of point-to-point Ethernet over SONET/SDH transport

There is considerable interest in using Ethernet over SONET/SDH (EoS) for Ethernet transport in a wide area network. EoS leverages the existing SONET/SDH infrastructure to provide efficient Ethernet transport with excellent OAM capabilities. In our initial evaluations and deployments of EoS, we have encountered some issues, as is common with any new technology. These issues include non-transparent transport of Ethernet information, lack of carrier-class performance monitoring and fault propagation, and non-standardized implementation of basic concepts. Vendors, service providers, and standards bodies should work together to resolve these remaining issues and thus bring forth the full potential of EoS.     

Key building blocks for high-capacity WDM photonic transportnetworks

The objective of this paper is to give an overview of the different studies we have performed at the research level regarding the design and implementation of a photonic wavelength division multiplexing (WDM) layer providing transparent transport services to client layers (SONET/SDH, ATM, etc.). Such a network requires a number of enabling factors to be assessed in order to become a reality. Among these factors are the availability of high-capacity WDM transmission systems and efficient optical routing nodes based on mature technology, the design of robust networks optimizing the utilization of resources, and the development of a management system in accordance with presently applied standards for transport networks. We review our achievements in these different fields     

基于SDH/SONET的IP数据传送技术分析

SDH/SONET是目前最主要的传输技术,网络应用则以IP业务为中心,IP在SDH/SONET上的传送是一个重要问题.本文讨论IP在SDH/SONET上传送的传统PoA和PoS技术的基础上,详细分析了两种新的协议--简单数据链路(SDL,Simple Data Link)协议和通用成帧规程(GFP,Generic Framing Procedure),研究了各种协议技术的优缺点.     

SDH以太共享环在城域网的应用

随着因特网和数据业务的爆炸性增长，城域网的主要业务正在从话音向数据转移。然而过去的城域传送网是为话音业务设计的，所以采用的是TDMM网络(SDH、SONET)。本首先介绍了基于SDH网络传送数据业务的几种新技术，如：POS、GFP、LCAS、RPR、共享以太环等，以及可以实现业务隔离、保证安全的VLAN、VLAN嵌套技术，然后对各种城域网数据传输技术进行了比较，最后分新了薪一代的MSTP设各府该具有的几个特点。     

Traffic engineering for ethernet over SONET/SDH: advances and frontiers

Continued growth in data services coupled with the entrenchment of existing carrier infrastructures have inevitably forced a convergence of SONET/SDH and Ethernet technologies. As a result, the very notion of Ethernet connectivity has expanded beyond traditional local area domains into broader metro/wide area settings. The key enabling advances have come in the form of improved SONET/SDH provisioning features as well as new carrier Ethernet services standards. These provisions have allowed carriers to build and deploy much improved multigrade point-to-point Ethernet line services and have also opened up new challenges for extended multipoint offerings. This article looks at this evolving area and summarizes recent advances in EoS traffic engineering. It also highlights some key future challenges and presents a novel scheme for multipoint services provisioning in EoS settings.     

Evolution of optical transport technologies: from SONET/SDH to WDM

It took roughly 10 years for the transport network industry to migrate from PDH to SONET. As this technology swap comes to an end, WDM technology is dawning, promising to revolutionize the network industry, with the possibility of transport bit rates above 10 Gb/s as well as transparency to signal encodings. However, a new wave of equipment upgrade is unlikely to happen as current SONET equipment is just beginning to pay off for its large investment. Thus, in years to come, SONET technology, the current standard for optical fiber access, will have to make room for WDM technology in a gradual way. On its part, WDM equipment must be developed to be backward compatible with SONET technology. This article discusses the requirements and issues involved in making WDM technology interoperable with SONET legacy equipment, as well as the evolution path toward a transparent optical transport network     

GMPLS controlled ethernet: an emerging packet-oriented transport technology

Most of the world?s traffic is now packetbased. While SONET/SDH transport technology continues to evolve, there are now major standardization efforts to develop a native packet-oriented transport technology. Ethernet, long dominant in the enterprise, is one of the fastest developing technologies for the transport layer. GMPLS, based on mature signaling and routing protocols, is gaining traction as a transport control plane, providing fast restoration and supporting automation of provisioning. We will briefly highlight recent Ethernet standardization and then introduce the concepts and standards work allowing GMPLS to control Ethernet.     

Survivable virtual concatenation for data over SONET/SDH in optical transport networks

Next-generation SONET/SDH technologies-namely, generic framing procedure, virtual concatenation, and link-capacity-adjustment scheme-enable network operators to provide integrated data and voice services over their legacy SONET/SDH infrastructure to generate new revenue. An important open research problem on data over SONET/SDH (DoS) is survivability: SONET automatic protection switching is too resource inefficient for data services, and the protection mechanisms of data networks are too slow for mission-critical applications. We propose two approaches for provisioning survivable DoS connections. Our approaches exploit the tradeoff between resource overbuild and fault-recovery time while utilizing the inverse-multiplexing capability of virtual concatenation to increase backup sharing. Our results show that one approach achieves low resource overbuild and much faster fault recovery than that of data networks, and the other approach achieves fast fault recovery comparable to SONET 50-ms protection (for typical U.S. backbone networks) while still achieving modest backup sharing. We further investigate the tradeoff between network blocking performance and network control and management complexity resulting from the number of paths M a connection can be inversely multiplexed onto: larger M leads to more freedom in routing and better network performance but increases network control and management complexity. Our results indicate that the network blocking performance for small values of M (e.g., M=2 for some representative backbone network topologies) is almost as good as the case in which M is infinity.     

新一代城域网解决方案

新一代SDH／SONET多业务传送技术和以DWDM和光交叉连接为主的光技术为运营商建设新一代城域网提供了良好的解决方案。本主要介绍了城域网的光传送技术的特点和富士通公司提供的最新全面解决方案。     

Future transport network architectures

The architecture of today's long distance transmission networks, which we call the baseline architecture, is a complex and multilayered hierarchy of TDM circuits. One premise of the baseline architecture is that restoration from network failures is provided mostly by SONET/SDH rings. This article presents an alternative architecture that uses ATM and optical layer cross-connect technology for TDM services. Using a sophisticated set of network design tools developed at AT&T Labs-Research, we show that the alternative architecture offers dramatic capital savings and improved network efficiency over the baseline architecture. Most of this savings can be attributed to use of OLXC mesh network restoration, which makes more efficient use of capacity than SONET/SDH rings, and use of ATM switching for transport of TDM circuits, which consolidates the numerous TDM equipment layers inherent to the baseline architecture. In addition, motivated by the rapid growth of IP services, we analyze in the alternative architecture whether to provide restoration for IP services in the IP layer itself, by rerouting packets over precalculated restoration paths with MPLS, or to alternatively provide restoration of failed IP layer links in the OLXC layer. One potential advantage of IP layer restoration is that network operators may choose to only restore a fraction of the services, in particular the “priority” services, affected by a network failure. This article gives some methodology of how to determine this fraction at which IP layer restoration is cost-competitive with OLXC restoration     

ATM交换机POS接入技术研究

POS即为Packet over SONET/SDH,是一种在同步光网络上承载IP数据的技术,也是当前因特网上一种重要的传输技术,该技术具有费用低、带宽利用率高、网络简单的优点,因此有广泛的应用前景。讲述了POS技术的原理,并结合ATM交换机,详细讨论了POS技术在硬件方面实现的原理及方法,在软件实现方面给出了功能单元、工作流程及设计要点。     

实现下一代SONET/SDH新业务的关键技术

本首先分析了SONET/SDH的现状，由此引出下一代SONET／SDH的新业务—DoS，接着指出几种现有的IP over SDH的缺点，在此基础上介绍实现DoS的关键技术——GFP、VC、LCAS，最后分析讨论了这些新技术相对于现有技术的优势。     

Reliability models of a class of self-healing rings

SDH/SONET technology provides the economical and convenient deployment of fault-tolerant high-speed telecommunication networks. This paper analyses a class of SDH/SONET self-healing rings (SHR), i.e. bi-directional SHRs (with two and four fibres) and uni-directional SHRs (including line-switched USHRs and path-switched USHRs). We derived, for both the two-terminal and the all-terminal, reliability models of the above mentioned SHR architectures.     

基于SONET/SDH的存储网络容灾技术分析

文章分析了存储网络（SAN）容灾技术，认为在某些企业中，数据是至关重要的资产之一，是业务系统运行的血脉．保护企业的重要数据是企业成功的关键因素。文章讨论了设计容灾技术解决方案应考虑的各种因素，并给出了基于SONET／SDH的存储网络技术的体系架构设计方案。     

Silicon bipolar chipset for SONET/SDH 10 Gb/s fiber-opticcommunication links

High-speed multiplexers, demultiplexers, frequency dividers, mixers, and amplifiers are key electronic components in high-speed fiber-optic communications systems such as SONET/SDH. In this paper, we present several important digital and analog integrated circuits (IC) which have been developed for use in SONET/SDH 10 Gb/s optical communication links. The circuits have been fabricated in MOSAIC 5E, an advanced silicon bipolar technology (f_T=26 GHz). The resulting chipset which amounts to a total of 10 IC's consists of multiplexers, demultiplexers, a regenerative frequency divider (2:1), a dual output limiting amplifier, and two different types of mixers for clock extraction. Specifically, the design and performance of these IC's and a hybrid clock recovery module are discussed. The high performance and potential low cost of this research chipset show that advanced silicon bipolar circuit technology can play an important role in future multigigabit fiber-optic communication systems     

广电IP over SDH的应用探讨

分析了SONET/SDH网络的现状和IPoverSDH的优势及工作原理 ,提出了IPoverSDH技术在泰州广电网中的应用方案 ,并探讨了相关技术。     

Interoperability update: dynamic ethernet services via intelligent optical networks

This article describes the 2005 Worldwide Interoperability Demonstration held by the Optical Internetworking Forum and showcased during SUPERCOMM 2005, The event highlighted Ethernet services transported over intelligent optical networks, using equipment from 13 of the industry's leading vendors located in seven carrier laboratory facilities around the world. The demonstration utilized a distributed optical control plane based on OIF Implementation Agreements to control a multilayer network providing Ethernet over SONET/SDH adaptation and transport. The article describes the global test network, services, architecture, and overall test approach. It also describes innovations made to the optical control plane to handle multilayer signaling and lists further refinements needed to make these services operational.     

Single-chip 622-Mb/s SDH/SONET framer, digital cross-connect andadd/drop multiplexer solution

This paper presents a single-chip all-CMOS solution for 4×OC-3c, OC-12, and OC-12c synchronous digital hierarchy/synchronous optical network (SDH/SONET) framing with integrated serial line interfaces. Outstanding features of this chip are clock and data recovery and fulfillment of ITU-T and Bellcore jitter requirements for SDH/SONET systems, as well as the large range of functions offered. These functions include asynchronous transfer mode (ATM) and point-to-point protocol (PPP) support, as well as built-in native SDH/SONET functions such as digital cross-connect, add/drop multiplexing, and automatic protection switching. In addition, the chip is based on a new scalable modular architecture     

Wavelength Assignment to Minimize the Number of SONET ADMs in WDM Rings*†

Optical wavelength division multiplexing (WDM) rings are being deployed to support SONET/SDH self-healing rings. In such systems, multiple SONET/SDH self-healing rings are realized over a single physical optical ring through wavelength division multiplexing. The cost of such a system is dominated by the SONET add/drop multiplexers (ADMs). To minimize the system cost, algorithms must be developed to assign wavelengths to lightpaths in the system so that the number of ADMs required is minimized. This problem of optimal wavelength assignment to minimize the number of SONET ADMs is known to be NP-hard. Existing heuristic algorithms for this problem include the assign first heuristic, the iterative matching heuristic and the iterative merging heuristic. In this paper, we develop an integer linear programming (ILP) formulation for this problem, propose a new wavelength assignment heuristic, and evaluate the existing and the newly proposed heuristic using the ILP formulation. We conclude that the performance of the newly proposed heuristic is very close to optimal.